This invention relates to a bumper/muffler assembly wherein a muffler, preferably made from a composite material, is associated with a vehicle bumper.
U.S. Pat. No. 5,726,398 to Zahn et al. discloses a bumper/muffler assembly. A portion of the structure defining the muffler also forms part of the bumper and, hence, must be capable of absorbing high impact loads. If, after a certain period of vehicle operation, the muffler becomes defective and must be replaced, those defective parts must be replaced with costly parts capable of performing dual functionsxe2x80x94attenuate acoustic energy and absorb high impact loads. The ""398 patent also teaches that the bumper/muffler assembly may be formed from metal, see column 2, line 41. There are inherent limitations from a design standpoint regarding possible shapes and sizes for metal mufflers. Hence, the ability to design mufflers capable of being received in irregularly shaped vehicle recesses or cavities is restricted. It is also noted that the tooling costs for metal mufflers is very high, which is problematic where only a limited number of mufflers are to be produced, e.g., less than 100,000.
Published International Application WO 99/27238 discloses a silencer formed from a composite material, such as a glass filled nylon (nylon 66). It does not, however, teach incorporating such a device into a vehicle bumper.
Hence, there is a need for an improved, low-cost muffler, which is capable of being associated with a vehicle bumper. Preferably, the muffler is made from a lightweight material, not required to absorb high impact loads.
These needs are met by the present invention, wherein improved bumper/muffler assemblies are provided. In these assemblies, the muffler outer shell may be formed from a lightweight metal or a composite material. Such materials are typically less expensive than thicker metals designed to also absorb high impact loads. Composite outer shells are further advantageous as tooling costs for such parts are typically lower than for metal parts. Furthermore, composite outer shells can be more easily designed and formed into intricate shapes and sizes so as to be received in irregularly shaped vehicle recesses and cavities.
In accordance with a first aspect of the present invention, a bumper/muffler assembly is provided comprising a bumper, and a muffler having an outer shell formed from a composite material. The muffler is associated with the bumper. That is, the muffler is a separate element from the bumper but is coupled thereto or is formed as an integral part of the bumper. The perforated pipe may include openings formed by completely removing small metal portions from the pipe. Alternatively, the perforated pipe may comprise a louvered pipe, wherein the openings are formed by cutting and subsequently bending small sections of the pipe outwardly. The bent sections typically remain attached to the pipe.
The muffler further comprises a perforated pipe for receiving exhaust gases, and fibrous material provided within the outer shell between the perforated pipe and the outer shell. The muffler shell may comprise a single or multi-piece outer shell. For example, the muffler shell may comprise first and second shell parts.
The fibrous material may comprise first and second fibrous material preforms which are received respectfully in the first and second shell parts. Alternatively, the fibrous material may comprise a loose or bagged fluffed-up, wool-type product provided within an internal cavity of the outer shell. It is also contemplated that the fibrous material may comprise a mat product wrapped about the perforated pipe or otherwise filling the internal cavity of the outer shell.
The bumper/muffler assembly may further comprise a heat shield positioned between the bumper and the muffler outer shell and/or between the bumper and an exhaust pipe. It may also comprise at least one bushing for holding a portion of the perforated pipe within the outer shell. The assembly may additionally comprise a cover for securing the muffler to the bumper.
The bumper may comprise a main body having front, rear, upper and lower surfaces. The front surface faces away from a vehicle. The rear surface faces toward the vehicle. The upper surface faces away from ground and the lower surface faces toward ground. The main body further includes a recess formed in the rear surface and one of the upper or lower surfaces for receiving the muffler shell such that the main body provides impact protection for the muffler shell. A portion of the main body may define at least a part of an outer shell of the muffler.
In accordance with a second aspect of the present invention, a bumper/muffler/exhaust pipe system is provided comprising a bumper/muffler assembly, at least one exhaust pipe and a flex section. The bumper/muffler assembly includes a muffler having an outer shell and a perforated pipe extending through the outer shell. The muffler is associated with the bumper. The flex section couples the exhaust pipe to the perforated pipe.
The flex section may be welded, clamped or otherwise coupled to the exhaust pipe.
The bumper/muffler/exhaust pipe system may further comprise a bushing having an outer surface engaging the outer shell and an inner surface engaging the flex section. The flex section may extend only part way through the bushing such that it abuts the perforated pipe. It is also contemplated that the flex section may extend completely through the bushing.
The flex section may comprise a flexible woven metal tube.
In accordance with a third aspect of the present invention, a bumper/muffler assembly is provided comprising a bumper, and a muffler. The muffler is associated with the bumper and includes an outer shell and a perforated pipe with opposing ends. The perforated pipe extends through the outer shell. At least one bushing assembly is positioned between the outer shell and the perforated pipe. The bushing assembly includes a first bushing having an angled outer surface. The first bushing is fixedly coupled to the perforated pipe. The bushing assembly further includes a second bushing having an angled inner surface and is positioned over the first bushing. The second bushing engages an inner surface of the outer shell and is capable of moving relative to the first bushing and the outer shell. A spring is fixedly coupled to the perforated pipe and engages an inner, side surface of the second bushing for biasing the second bushing outwardly toward a corresponding end of the perforated pipe.
In accordance with a fourth aspect of the present invention, a bumper/muffler assembly is provided comprising a bumper, and a muffler having an outer shell formed from a non-high impact resistant material. The muffler is associated with the bumper. The outer shell does not comprise a high impact-resistant structural component of the bumper.